The present invention relates to components employed in the manufacture of gun ammunition and particularly rifle or pistol ammunition for weapons of 50 caliber or less having rifled barrels.
In all gun ammunition wherein a projectile is propelled from a rifled barrel of a weapon, the projectile spins about its longitudinal axis (about its trajectory) at high speeds of rotation. Consequently, it is of major importance that the density of the projectile be uniform in any given plane taken normal to the longitudinal axis of the projectile so that the projectile does not wobble (nutate) as it is spinning to its target. Wobble of the projectile can adversely affect both the terminal ballistics of the projectile and, more importantly, the accuracy of delivery of the projectile to the target. Severe non-uniformity of the density distribution of the projectile about its longitudinal axis can result in jamming of the projectile within the gun barrel, or in less serious wobble, damage to the lands of the rifling of the gun barrel. Accuracy of delivery of the projectile to a target also dictates that the projectile be of consistent construction, including weight, from projectile to projectile so that a consistent given load of gun powder employed in each round of ammunition will ensure that each round of ammunition functions precisely like each other round of the ammunition. In certain situations, such as sniper fire, it is imperative that the shooter be confident that each round of ammunition will perform precisely like every other round of ammunition for a given weapon for the reason, among others, that the sniper commonly can only get off a single shot to his target. This same situation exists in sport hunting and in competitive shooting.
Of recent vintage is the concept of gun ammunition wherein a round of ammunition includes a projectile that includes a metallic jacket having a core disposed therein, wherein the core is formed from compressed powder or a mixture of powders. Initially, the jacket is in the form of an elongated cup. In this type projectile, a preformed core or plurality of cores are loaded into the jacket through the open end thereof and pressed into conformity with a portion of the interior volume of the jacket. One major concern attending these powder-based projectiles is the accuracy with which the projectile is delivered to a target.
In the art, prior to the advent of powder-based cores, the entire projectile was form ed from lead or other metal. Formation of these projectiles was relatively simple and involved molding of molten metal. This procedure also ensured uniformity of distribution of the density of the lead or other metal throughout the projectile, including uniformity of distribution of the density relative to the longitudinal centerline of the projectile.
In the manufacture of powder-based projectiles, however, there is a major problem associated with attainment of uniformity of the density of the projectile throughout the projectile. For example, the uniformity of the density of a powder-based projectile is affected first in the initial compaction of the powder into a core, second, in the pressing of the core into the jacket to ensure uniform filling of that portion of the interior volume of the jacket which is to be occupied by the core, and third, die forming of the core and jacket for purposes of closing the open end of the jacket (either partially or wholly) and/or defining the geometry of either the trailing end and/or the leading end of the projectile.
Other considerations in the forming of powder-based projectiles include the propensity of the powder to become dislodged within the jacket and thereby diminish the desired uniformity of distribution of the density of the projectile about its longitudinal axis. Another consideration associated with powder-based cores arises when the projectile includes a partially-open leading end of the jacket, particularly where the projectile is provided with an ogive at the leading end of the projectile. In this situation, the formation of the ogive must of necessity take place after the core or cores are loaded into the jacket. Die forming of the ogive is the most commonly used technique for forming the ogive. As the core and jacket are deformed to define the ogive, a small portion of the leading end of the core tends to disintegrate into loose powder particles.
The present inventor has heretofore employed a solid metal disc inserted within the jacket and in overlying relationship to the leading end of the core. This places the disc within the region of the projectile which is formed with an ogive so that the disc is itself deformed, along with a portion of the leading end of the core and a portion of the leading end of the jacket, in the course of die-forming the ogive. This prior disc was of tin or other readily deformable material, preferably a metal. The disc desirably was of substantially uniform density throughout the disc, and especially of uniform density distribution within any given plane normal to the thickness dimension of the disc. These prior discs were formed by a process which included repeated rolling of a sheet of metal, tin, for example, until its thickness was precisely of the desired thickness of the disc. Moreover, this rolling of the sheet of metal has been found to be important for obtaining uniformity of the density distribution of the sheet. Individual discs were heretofore die-punched from the sheet. Such die-punching has been found to, at times, develop a flashing around a perimetral edge of the disc, such flashing tending to be non-uniformly distributed around the edge of the disc. These factors, among others, have presented problems of cost as well as consistency of the density distribution within a jacketed projectile.
It has also been found that solid, particularly metal, discs tend to be driven inwardly of the projectile (along the longitudinal axis of the projectile) when the projectile strikes a solid or semi-solid target, with no disintegration of the disc. In those projectiles where frangibility of the projectile upon its striking a target is desired, this failure of the disc to fully disintegrate detracts from the desired terminal ballistics of the projectile. More importantly, this solid disc becomes a projectile itself and possesses sufficient energy to injure, even kill, an unintended human, for example.
It is therefore an object of the present invention to provide an improved disc for incorporation into a projectile for gun ammunition.
It is another object of the present invention to provide a method for minimizing the non-uniformity of density distribution of a multi-component projectile relative to the longitudinal centerline of the projectile.
Other objects and advantages of the present invention will be recognized from the description contained herein, including the drawings and the claims.